Continuous pressure separating



Feb'. `18, 1941. R. THOMPSON 10,121,723

CONTINUOUS PRESSURE SEPARATING DEVICE Original Filed Jan. l0, 1933 13Sheets-Shet 1 Feb. 18, 1941. R. M. THoMPsoN Re. 21,723

COTINUOUS PRESSURE SEPARATING DEVICE Original Filed Jan. 10, 1933 13Sheets-Sheet 2 aso 393 389 /l/ INVENTOR obefI/V. 77701224050 www `ATTORNEY Feb. 18, 1941. R M THQMPSQN Re. 21,723

CONTINUOUSPRESSUHE SEPARATING DEVICE Original Filed Jan. l. 1955 15Sheet-s-Sheet 5 i 6A /95 I -f ,wifi/ifi!! l [40J v' my. .s

Feb. 18, 1941. R M. THOMPSON l A Re- 21,723

Y CONTINUOUS PRESSURE SEPARATING DEVICE i original Filed Jan. 1o, 195:513 sheets-she@ 5 I lNvEN-roR ATTORNEY Feb. 18, 1941. y R, M THOMPSQN Re.21,723

CONTINUOUS APRIEJSSURE. SEPARATING DEVIQCE Original Filed Jan. 10. 193313 Sheets-Sheet 6 31mo4@ @3% o INVENTOR Feb. 18, 1941. R. M. THOMPSON R21,723

CONTINUOUS PRESSURE SEPRATING DEVICE l Original Filed Jan. 10. 1953 13Sheets-Sheet 7 1N V EN TOR.

allvgeff Tompson ATTORNEY Feb. 18, 1941 R. M. THOMPSON Re- 21,723

CONTNOUS PRESSURE SEPRATING DEVICE Original Filed Jan. 10. 1933 13Sheets-Shea?r 8 les,

INVENTOR oerf. Thompson ATTORNEY Feb. 18, 1941. R. M. THOMPSON Re 21,723

C ONTINUOUS PRESSUI'IE SEPARATING DEVICE origamall Filed Jan. 1o, 195s13 sheets-sheet 9 INVENTOR ATTORNEY Feb. 18, 1941. R. M. THOMPSON Re-21,723

'CONTINUOUS PRESSURE SEPARATING DEVICE Original Filed Jan. 10, 1953 15Sheets-Sheet 10 IN VEN TOR.

l/lz Robez'i T/.Pompson ATTORNEY Feb. 18, 1941. R. M. THoMPsoN Re-211723 CONTINUOUS PRESSURE SEPARATING DEVICE Original Filed Jan. 10,19355 ,lsheets-'Sheet 1l I llllllflllll ooooooQGQlO0000 ssa INVENTORATTORNEY Feb. 18, R. M THMPSON Re. 21,723

CONTINUOUS PRESSURE SEPARATING DEVICE Original Filed Jan. l0, 1933 13Sheets-Sheet 12 INVENTOR 2896611 M T /zompso I /34 2a@ o .1 f f l 1 my.43 ATTORNEY Y Feb. 18, 1941. R. M. THOMPSON Re 21,723

CONTINUOUS PRESSURE SEPARATING DEVICE Original Filed Jan. 10, 19325v 13Sheets-Sheet' l5 IIIAIIIIIIIIIIIL VIIIIIIl/II A 205 JNVENTOR gaberf".T/lompson Y ATTORNEY Reissued Feb.y 18, 1941r Re. 21,723 'y CONTINUOUSPRESSURE SEPARATING DEVICE Robert M. Thompson, Seattle,iWash., assignerto Thompson Continuously Operating Filter Press Company, a corporationof Washington Original N0. 2,112,869, dated April 5, 1938, Se-

rial No. 650,990, January 10, 1933. Application i'or reissue September23, 1938, Serial No.

36 Claims.

My invention relates to the art of devices designed to separate uids orliquids from other fluids or liquids of greater fluidity and uids orliquids from solids.

More particularly, my invention relates to a combined press and lterpress or to a press designed for continuous operation which ischaracterized by the development of extremely high pressures andpractical and eiilcient operation. Particularly does my invention relateto simplifying and reducing the cost of the filtration or fil trationstep in the industrial arts, which step at present constitutes one ofthe expensive operations in manufacturing. The invention in generalrelates to the art of filtering or filtration disclosed in Patent No.1,778,342, issued to me October 14, 1930 and in my application, Ser, No.509,595, Patent No. 1,997,611, issued to me April 16, 1935.

Itis common practice in the art of filtration to refer to devicesdesigned for the separation of materials by the application of force orpressure tothe materials from without, as "presses; while devicesdesigned for the separation of materials by' having the force or'pressure transmitted through the materials themselves as filter presses.Filter presses are usually used where the amount of solids to beseparated is but a small proportion of the total mobile mass. composedof said solids and liquids in which said solids are disposed and hencethe said materials are pumped into the tler press. Presses on the otherhand. are used where the proportion of solid matter is much greater inrelation to that oi' the liquid composing said materials to be filtered.The distinction between the two devices willdevelop clearly in thefollowing paragraphs.

By rendering the filtering continuous, my device herein disclosedprovides for utilizing the filter press principle with materials inwhich the solids are the predominant percentage of the material beingtreated. 'I'hls is lust the reverse of the common practice. Heretofore,the devices in common use for materials having only a small percentageof liquids, has been the press type rather than the illter press type.By providing for relatively excessively high pressures and fluid tightchambers and continuous discharge of cake in a filter press type ofdevice, themachine embodying my invention herein set forth, has solvedone of the difficult steps in -manufacturing processes.

In the industrial arts filtration is very often a costly item in themanufacturing process. This is due 1n part to the intermittent characterof the operation of the filter devices and to the large amount of manualattention which is incident thereto. Moreover, in the filtering processthere are points at which the expressed liquids are more clear than atother,4 points. The clearer liquids are usually obtained during the'later stages of the separating process due to the fact that theseliquids pass through the filtering me- 10 dium after a deposit of theretained solids on the filtering medium has accumulated, which retainedsolids usually forman important part of the filtering medium. The earlyliquids' expressed before the deposit of said solids in the 15 form of alter on the filter cloth or medium may be cloudy. By separately drawingon the cloudy Aportion of the expressed liquid during the early stagesof the filtration process, a minimum quantity of the cloudy filtrate isretained with the clear filtrate.

Objection obtains to the devices as heretofore designed in the leakagethat takes place by the joints formed between the stationary parts andmoving parts of the device. Also serious objec- 25 tion obtains to thefriction developed between said parts. This friction results inexcessive .wearing away of the filter cloth as well as other parts.

Aas heretofore in common use are not capable of this dual use. Thisinvolves the installation of bot-h devices which involves great expenseas well as the loss of important floor space. l 4 4The general objectsof my present invention are to overcome the objectionsr to prior devicesof the nature hereinabove pointed out and to generally improve andincrease the eliciency of continuous presses and filter presses, as Wellas to 45` provide new means and modes of operation with new results.

Another important object of my invention is to provide an upright orsubstantially vertical press or filter press of this nature embodyingtwo pend- (it)A ent press members, pivotally supported from their upperends, between which press members the material passes while beingfiltered, said press members being connectedA with each other by.transverse iloatingly mountedtie means, whereby 55 the heavy pressuresproduced between the two press members are counterbalanced at frequentintervals or section by section without being transmitted to other ormounting parts of the frame. This tie means may include springs capableof yielding to pressure exerted between the two pendent press members.

Another object is to provide equalizer means in connection with both thetop and bottom of the pendent press members for compelling equalmovement of said press members toward and away from the ycentral medialvertical plane of the machine at all times, the upper equalizing meanspreferably being in the form of manually operated adjusting mechanismand the lower equalizing means preferably being automatically operatedin response to pressure.

, Another primary object is to provide a press and iilter press of thisnature having a filter 20 chamber formed by four belts, all moving inthe same direction and at substantially the same rate of speed, wherebywear and needless consumption of power. due` to friction is reduced to aminimum, vand the problem of preventing leakage of liquids even underrelatively excessively high as well as ordinary pressures is very muchsimplied, two of said belts preferably being of material impervious tothe passage of liquid and being supported by resilient. means. l

A further object is to provide for the application of intermittent orperiodic increase of pressure to the material being treated, wherebyshort drainage periods are afforded during the intervals Awhen thepressure is relatively sustained but. not increased, as well as duringsuch periods of increasingt-he pressure. The preferred means foreffecting such periodic action may be in the form of a ratchet drive fortransmitting the power to the filter means, said ratchetdrive affordingan 40 intermittent drive of relatively slow and readily variable speed.

Other and more specific objects are to provide eiiicient self-adjustingplug means for maintaining a substantially liquid tight contact with the45 moving belts; to provide suction means forpicking up any liquid whichescapes around the plug means; to provide new and eiiicient means forpicking up or collecting the liquid filtrate after it has passed throughthe filter cloths and slats 5 (to prevent reabsorption of the liquid -bythe solid matter (cake) during its emergence from the pressure zone) toprovide types of slatmembers for slat'belts new as toform and construc-`tion, whereby the withdrawal. of itrate away 55 from the pressing faceof the slats is facilitated;

to provide for employing traveling porous absorbent means as anassistance to carrying through the pressure chamber the material beingtreated and promoting the drainage of the uid 60 part of the material;and to provide automatic means for governing the speed and the rate offeed tothe machine in proportion to the thickness of the cake or layerof solid matter in the machine at the point of maximum pressure.

v65 'ine above mentioned general objects of my invention, togetherwith.others inherent inA the: same, are attained by the mechanismillustrated 75 Figure 2 is a side elevation of the same.

Figure 3 is a vertical section substantially on broken line 3-3 of Fig.2.

Figure 4` is a cross section substantially on broken line 4-4 of Fig. 3.

Figure 5 is a cross section substantially on broken line 5 5 of Fig. 3.l

Figure 6 is a detached elevation from the outer or rear side of theframe/of one of the main .pendent press members.

Figure 'l is an edge view of the same.

Figure 8 is a cross section substantially `on broken line 8 8 of Fig. 6.

Figure 9 is a detached elevation of a frame rail used to vsupport theimpervious side belts of my machine.

Figure l0 is a, detached plan View of a filtrate pick-up device used inmy invention.

Figure 11 is a sectional view substantially on broken line II-II of Fig.10.

Figure 12 is a detached cross section of a cup like packing plugused inthe upper portion of my pressure chamber to form a seal against theescape of liquids, a leather packing cup being shown.

Figure 13 is a fragmentary view partly in section and partly inelevation of the upper portion of my press and filter press, showing apreferred form of packing plug means in end elevation.

Figure 14 is a detail view partly in elevation and partly inlongitudinal section of va preferred form of multiple packing plug usedin my machine. V

Figure 15 is a cross section substantially on broken line |5-I5 of Fig.14.

Figure 16 is an inverted fragmentary plan view of one of the packingplugs shown in Figs.' 14

and 15. l A.

Figure 17 is a fragmentary sectional view through the side belt rail andside belts, showing a fragment of the main lter belts in the position inwhichthey make sealing contact with the side belts.

Figure 18 is a front elevation, with parts broken away, of one form ofslat for the main slat belts, a wire mesh being used on the face of saidslat.

Figure 19 is a 1sectional View on broken line l9-l9ofFig. 18.

Figure 20 is a fragmentary sectional view substantially on broken line2li- 2n of Fig. 18 illustrating details of the drainage means of theslat shown in Figs. 18 and 19.

Figure 21 is an end view of said slat.

Figure 22 is a plan view with parts broken away of another form'offilter belt slat in which a slotted plate is used on the face of theslat.

Figure 23 is an edge view of the slat shown in Fig. 22.

Figure 24 is a sectional view substantially on broken line 24-24 of Fig.22.

Figure 25 is a sectional View of a preferred form of filter belt slat ofrhomboidal shape in cross section to afford Walls which are inclineddownwardly from the face to the rear of said slat to promote drainage ofliquid.

Figure 26 is a fragmentary elevation of a perforated plate which may beused on the lter belt slat shownv in Figs. 18 to 21 in place of the wiremesh plate shown in said Figs. 18 to 2l.

Figure 27 is a sectional view of still another form of filter belt slatin which said slat is of rhomboidal shape in cross section to aifordwalls .which are" inclined downwardly from the face to the rear of saidslat to promote drainage of a liquid, and inwhich a plat of porous-iilter ma- Figure 29 is a fragmentary cross section on.

broken line 2.-29 of Fig. 28.

Figure 30 is a sectional view on a larger scale substantially on brokenline 30-30 of Fig. 28.

Figure 31 is a detached elevation illustrating one means for varying thespeed oi the ratchet drive and one means for compelling an equal travelof each ratchet arm.

Figure 32 is a detached fragmentary elevation illustrating one centeringmeans which may be used in connection with the ratchet drive.

Figure 33 is a detached fragmentary elevation of other centering meansfor the ratchet drive.

Figure 34 is an elevation showing means for varying either the feed ofthe machine or the speed of movement of the belts, or both,automatically in proportion to the thickness of the cake or body ofsolid matter between the iilter belts at the location where said cake'ismost highly compressed.

Figure 35 shows a modified form of my invention in which the filter-belts are supported on chain mesh belts, which, in turn, are supportedon rollers, the chain mesh rbelts taking the place of the slat beltsshown'in the preceding figures. 'Ihis iigure also shows a movablecarrier member in the nature of a very porous fabric disposed betweenthe filter belts, said carrier member pro- Figure 39 is a cross 'sectionsubstantially on line 35-38 of Fig. 38.

Figure 40 is an enlarged detail showing the flexible means forsupporting the packing plug between the four moving lter belts in such a-manner as to insure an equal pressure of the plug against all filterbelts.

Figure 41 is a somewhat diagrammatic side elevation of another modiedform of ratchet drive for my combined press and filter press in whichthe ratchet levers are connected directly to the crank arms.

Figure 42 is avfragmentary plan view of parts of a bevel gear drivewhich may be used for the side chains of my combined press and filterpress.

Figure 43 is a view partly in section and partly in elevation showingthe complete drive of the bevel gear mechanism shown partly in Fig. 4,2.

Figure 44 is a somewhat diagrammatic side elevation illustrating onemeans of guiding' iilter belts into my combined press and filter press.

Figure 45 is a fragmentary sectional view showing an alternative springsupporting structure for the main pendent frames. Y

Figure 46 is a cross section through a side framel of my machine showinga coil spring resiliently supporting the side belt rail, said coilspring a1'- fording greater travel and being less subject to breakagethan the flat springs shown in Figs. 4 and 1'7.

Figure 47 is a somewhat diagrammatic side elevation showing a modiedform of my4 invention in which one of the pendent frame members is amasthese bearings.

xedly and adiustably secured at its lower end to a non-movable partofthe frame.

Figure .48 is a fragmentary sectional view of a modiiied form of theinvention in which the impervious moving side belts are dispensed withand a highly polished non-movable plate is substituted in place thereof.v

Figure 49v is a somewhat diagrammatic view partly insection.and partlyin elevation, showing means for supporting the impervious side beltmeans with a pressure which varies in proportion to the pressure in thelter chamber.

Referring particularly .to Figs. 1 to 17, inclusive, wherein I haveillustrated one embodiment of my invention', I show a Amain frame formedof two upright parallel, spaced apart, channel shaped side members IIBprovided with base members I I I and rigidly connected at their bottomends by a cross plate II2, see Fig'. 2. At their upper ends the sidemembers III each have an angle bar |I3 secured thereto. These angle barsextend at right angles to the member IIU and are rigidly securedtogether by transverse vplates III positioned near the outer ends ofthef angle bars |I3. A.' transverse angle bar IIS (Fig. 3) also extendscross wise between the top ends o1' the side frame members IIIl andcooperates with the transverse plates I I4 in rigidly connecting the twoupper ends of the spaced apart side members IIII together. The angle barIIS also provides support for .a packing plug hereinafter described. Thepreviously described parts form a rigid stationary and substantialframeon which the apparatus hereinafter described may be mounted.

. l35 Two pendent frame members, designated gentioned in depressions H9'in plates |20' which rest slidably on brackets |20 and permit the smallamount of swinging movement required by the pendent frames. I'he pivotalsupports which are thus formed for the pendent frame members IIS arelocated near the upper ends of said frame members andiin substantiallyvertical alignment between upper bearings I2I and lower bearings |22,see Figs. 6 and 7, which are provided on these frame members. The upperbearings I2 lare adjustably supported from shelf like portions4 |23 atthe upper ends of the pendent frames IIB by adjustable screw and nutmeans I 24. This makes it possible to adjust the tension of slat belts,

hereinafter described, which are supported by The pendent frames,hereinafter also called strongbacks, IIC are essentially of strong andrigid construction, designed to withstand heavy pressure. They arepreferably each formed of an upright medial plate portion |25 having arelatively fiat plane inner face provided with track members |28.Reinforcing cross members' |21" of.' substantially U shaped crosssection are rigidly connected with the medial plate portions |25 andextend crosswise of the rear sides thereof at spaced apart intervals.Longltudinally extending web `members |28 extend along the rear side ofthe medial plate portions built up of a plurality of pieces weldedtogether,

|25 and through the cross members |21, as more clearly shown in Figs. 4,6, 7, and 8. The medial plate portions |25 of the pendent frame membersare provided with openings |23 positioned between the U shaped crossmembers, through which openings, liquid may be taken ofi', ashereinafter described. The .outer ends of the U shaped cross members areprovided with tie rod holes |30, as more clearly shown in Figs. 6 and 8.The pendent frame members IIB, are shown as but it will be understoodthat they may be cast in one piece, if the use permits.

The bearing members |2| at the top ends of the pendent frames ||8support shafts |3| and |32 upon each oi' which shafts are mounted twospaced` apart sprocket wheels |33. The lower bearing brackets |22support shafts |34 and |35, upon each of which are mounted two spacedapart sprocket wheels |36. A greater or less number of sprocket wheels|33 and |38 maybe provided on each of the respective shafts if desired.The lower sprocket wheels |38 are keyed to the shafts |34 and |35 asshown in Fig. 5yand theupper sprocket wheels |33 may be similarly keyedto their shafts I3| and |32.

Two endless slat belts are operatively mounted on the sprocket wheels|33"\and |38 and are supported on the pendent frames ||8 in such amanner as to cooperate with other parts in forming a pressure or filterchamber |38 having as two sides the two opposed and adjacent portions ofsaid slat belts. 'Ihis pressure or iilter chamber |38 is wider at thetop and converges toward the lower end inY such a manner that materialwhich is introduced at the top end will be subjected to increasingpressure as it moves downwardly through said chamber. The opposedportions of the slat belts which form walls of the pressure chamber |38move downwardly in the operation of the machine.

'Ihe slat belts are formed of transverse slats designated generally by|39. 'Ihese slats are secured to link belts |40 which run on thesprocket wheels |33 and |38. The link belts |40'have rollers |4|, seeFigs. 44 and 5, at the locations where the links of said belts areplvotally connected, which rollers run on the track members |26 andserve as an antifriction means for supwith drainage means wherebyfiltrate expelled from material within the chamber |38 may readily passoutwardly through said. slats. Several forms of these slats are shown inFigs. 18 to 30, inclusive. WhereA reference is made in thisspecification to top edge and bottom edge of these Islats,'it will beunderstood that these terms refer to the slats in the positionin whichthey form the filter cloth supporting means or walls of the filterchamber.l it being obvious that these slats are reversed in position asthey pass around the upper and lower sets of sprocket wheels |33 and|38, respectively.

These slats have three importantfunctions; first, they form `supportingmeans to withstand Rollerv or ball bearings ofA cloths or belts; second,they serve tocollect and direct the liquid filtrate to a deniteposition; third, they serve to `drain the ltrate promptly away from thefilter cloth or slat face. In every y case the cracks between the edgesof adjacent slats slope downwardly and away from the filter chamber, dueto the fact that the lter chamber is'slightly wedge shape or convergentfrom top to bottom. This slope is greatly accentuated in the rhomboidalform of slat shown inFig. 27.

The slat shown in Figs. 28, 29 and 30 is one form of slat which may beused. This type of slat may be of non-metallic material, as of hardwordmade liquid proof by subjecting it to a hotparafllne bath. 'I'his slathas holes |42 for the reception of suitable bolts, not shown, by whichsaid slat may be secured to the link belts |40, The holes |42 arecounterbored as at |43A on the front side of the slat for the receptionof the bolt heads. This slat |39 isfurther. provided, on the sideagainst which the filter belt is pressed, with spaced apart longitudinalgrooves |44, which extend from the ends of the slat to a point near thecenter and are connected, by a,

transverse intersecting groove |45, with drain holes |48, which drainholes extend from face to rear of the slat and afford passagewaysthrough which filtrate may be passed through the slat, so that saidfiltrate may be picked up at the rear side thereof. Each groove |44preferably has a saw kerf |41 in the bottom thereof so that if a filtercloth is pressed into the groove, the saw kerf will still afford achannel for the drainage of liquidfto the holes |48. A packingmember |48in the nature of a thin fiat piece of resilient material, as rubber, maybe secured, preferably by cementing the same,to the bottom edge of eachslat. These packing members tend to pre-- vent leakage between theslats. The top edge of each slat is provided with a longitudinal recess|43 which communicates with a medially positioned transverse notch orgroove |50, whereby any filtrate which enters the crack between theslats is drained to the center and discharged to the rear of the slat.'Ihe packing members |48 and recesses |40V and |58 are more clearlyshown in Fig. 30, which is on a larger scale than Fig. 28. A pluralityof grooves |5| are provided in the backs of the slats for the purpose ofdraining, toward the center of the slat, any nltrate which may escapethe other grooves and trickle down the base of the slats. The grooves|5| are inclined downwardly from outer to inner ends and are cut at anyangle as illustrated in enlarged detail; Fig. 29, whereby they will formchannels in which the liquid may flow toward the center of the slats.When a filter cloth is pressed, against the front side` of this slat,said cloth will be supported by the lands'or surfaces |52 between thegrooves |44 and filtrate may be forced through said filter cloth intothe grooves `|44 and thence disposed of to the rear of the slats.

In Figs. 18, 19, 20 'and 21 I have shown a metal slat |53 provided withinternal cavities |54 having ribs |55 therebetween. The face side of theslat l53 is recessed to leave a narrow marginal Yportion |55 whichprojects beyond the plane common to the front edges of the ribs |55.Ther face of the slat may be formed rby a relatively the pressures whichare exerted against the filter the'slat |53 to-facilitate securing thesame to a l link belt. The wire mesh 51 serves as a support againstvwhich nlter cloth may be pressed. Liquid nitrate which is forcedthrough said nlter cloth presses readily through said wire mesh into thecavities |54. The front edges of the ribs |55 may be notched as at |58and |60, so that this liquid nitrate may now from the cavities |54 to acentrailylocated discharge opening |6| and be discharged through theback wall of the slat where it is picked up by liquid nitrate pick-upmechanism, as hereinafter described. The top edge of the slat |53-has a.depression |62 therein |65 forming an edge from which liquid will tendto drip, and the bevel |64 tending to prevent this drip from runningforwardly between'the slats.

' Grooves |64', having'the same purpose and function as the grooves inFigs. 28 and 29 may be provided in the rear wall of the slat |53.

- The space between the two lowermost hori-v zontal wires of the wiremesh member |51 is preferably nlled or otherwise blocked up orobstructed as shown at |66, Fig. 19, to thereby f form a lip or dam tocause the liquid nltrate to now rearwardly away from the wire mesh andto further prevent anyv residual nitrate from -running back into thenlter cloth as the slat moves away from the body of material which hasjust passed out of the pressure zone. A narrow ledge or dam |68'.positioned just inside of the bottom edge of the slat face |51 may beused instead of the nlling |66. Also, there may be provided a dam' |56',whereby nitrate which trickies down the screen may be maintained awayfrom the compressed solid matter of the material being treated formingthe cake and positively directed to passageways |61, providing positiveisolating for nitrate from the expanding vacuum-creating cake.Experience has taught that the nitrate tends to collect in the lowermeshes of the nlter face from which, unless provision such-as dam |56'is provided, itis reabsorbed into the cake by the vacuum action of theexpanding cake when the pressure is released. Passageways |61, Fig. 20,extend from the lbottom of the screen |51 to the bottom edge of theslat, whereby nitrate may be drained into the depression |62 in the topofthe next adjacent slat below. A vertical groove |68 is provided ineachend of each slat |53 near the front side thereof and one or more holes|69 are prohereinafter described and shown in Fig. 1'1, and i any liquidnitrate whichA is forced edgewise through this nlter cloth may enter thegroove |68 and pass into the inside of the slat through the holes |68.

When a wire mesh face |51 is used on the face side or the mier slats, as'shown 1n Figs. 1a m 21,

it permits the liquid nitrate to pass freely through the nlter clothswhich are pressed against said wire mesh, but I nnd that the heavy ofthe wire Vmesh |51.

pressures within the pressure chamber may stretch and eventear the nltercloth, by pressing it into the spaces between the wires. I overcome thistendency preferably by subjecting the wire mesh to a very high pressureto thereby flatten out said wire mesh before it is installed on thefaces of the slats. 'I'he flattening of the wire mesh affords a natterysurface and more bearing area for the nlter cloth and prevents injury ofthe nlter cloth. This flattening of the wires is shown in Fig. 20.

Fig. 26 shows a fragment of a perforated plate |10, which may be used onthe slat |53 in place One advantage of this perforated plate over thewire mesh |51 is that it affords a more even surface and there is lesstendency to stretch a nlter cloth which is pressed against the front .ofthe slat. By omitting or nlling one row of holes near the bottom edge ofthe plateA |10, as shown at |1|, the same result is obtained as by theuse of the nlter |66 in Fig. 19, a consideration particularly importantwhere excessive pressures are employed.

The slat |12 shown inFigs. 22, 23,'and 24 is also of metal constructionand has cavities |13 on the inside into which liquid nitrate may pass. Arib |14 extends lengthwise within said slat |12 and is flush with thefront edge of the slat. The face of the slat |12 is formed by a metalplate |15 which has slots |16 with rearwardly diverging walls and issecured to the slat |12 by screws |11. The slots |16 and the supportingsurfaces between said slots are of suitable shape, size and positioningso that liquid nitrate which is pressed through a nlter cloth, supportedby the plate |15, will pass through the slotsj|16 into the interiorcavities |13 of the slat andbe discharged from the rear side of the slatthrough openings |18. Openings I 18', shown'by dotted linesvin Fig. 22,may be -providedin the rib |14 for nitrate to pass through. 'Ihe slat|1-2 has holes |18 formed in enlarged portions of the rib |14 .throughwhich holes |18 bolts or cap screws |80 may extend for the purpose ofsecuring the slats |12 to the link belts. The heads of the cap screws|80 are positioned in openings |8| in the plates |12 and may benush-with the front side of said plates |12, see Fig. 24. The bottomedge of each slat |12 may have a.l packing strip |82 cemented orotherwise secured thereto, which tends to exclude nitrate from the spacebetween said slats. The top edge of each slat |12 may have a. depression|83 communicably connected with the interior of the slat by notches |84to catch anynitrate which nnds its way between the slats 4and to directsaid nitrate into the cav.- ity within the slat. A horizontal slot '|85is provided along the bottom of the plate |15 to afford a means forreceiving nitrate in a portion of the plate not otherwise provided withslots. The n1- trate entering the slot |85 passes down through openingsformed by notches |86 in the inner sideof the plate and will ordinarilynnd its way into the cavities of theAnext adjacent slat through thedepression |83 and notches |84. It will'be noted, in Figs. 22 and 24that the slots |16 ter' minate above the level of the bottom of theinterior cavity |13 of the slat |12, and that thel slot |85 is closed atthe innerside'by the edge of the slat, thereby leaving a lip or dam at.|81 which corresponds in purpose andl function with the lip or-dam |66in Figs.,l8 and 20, previously described. Drain holes |88 are providedin the back of each slat |12, preferably just below the t0? Wall andjust below the. rib |14 oi saidl s iat, to

facilitate washing out, cleaning and sterilization of the interiorcavities of said slats. It will be apparent that these drain holes |88will be in a suitable position to allow all-liquid to drain out ftheslats when the position of the slats is reversed after said slatshave passed around the lower sprocket wheels |33 at the beginning oftheir upward excursion and before they have passed around the uppersprocket wheels |36 at 4the beginning of their downward excursion.

This washing out may be done by directing a sprayof water through theslotted face of the slats as they are moving upwardly on the outer sidesof the machine, said slats then being free from the nlter cloth. The endwalls of the slats |12 are notched at the front edges, as at |89, Fig.

24, to afford passageways through which liquid nitrate in the edges of aniter cloth which extends around the ends of said slats may now into theslats. In Fig. 24 I also disclose a preferred method of mounting thelinks MII on .the slats j byncountersinking the base portion of eachlink into the siat, whereby the ends of the link portion IIB' will abutagainst solid metal shoulders in the slat and the tendency toshear onthe bolts |88 will be greatly lessened. v

'I'he filter beltsll (Fig. 24) contacting the slat faces |15 may betreated or impregnated to render them repellent to nitrate. An exampleof such a nitrate repellent material, when water constitutes thenitrate, would be a nlter belt made of a fabric in which the threads hadbeen treated or impregnated with paranln. A nitrate repeiflent fabric orbelt of this nature will cause the -nltrate which collects in the holesor slots 'of the siat face |15 to form globules 106 when said nitrate isexposed to the vacuum suction action arising from the expanding cakewhen pressure is released. When nitrate is thus induced to assume theglobular form, spaceis left between said globules for air to pass torelieve the vacuum like action without carrying said nitrate back intothe niter belt and into the cake. Treating the slat faces with nitraterepellent material, such as aluminum stearate, also renders these facesrepellent to the return of nitrate and helps to cause any nitrate in thepassageways in said slat faces where experience teaches it naturallyforms as a nim, to assume a globular form and y aiiowairtopass inwardlywithout carrying the ni of rhomboidal form in vertical cross section,the

' top and bottom of said slats'being inclined downwardly and backwardlyfrom the face of the Slat to thereby promote rapid drainage of -nitratefrom face to back, both within the siat and between the respective slatsin the niter zone. 'I'he said rhomboidai form of the slat has beenfound,

by experience, to be a most important change in preventing-there-absorption of the expressed nitrate by the vacuum created 'by theexpanding cake when thepressure is released and in .in-`

cursion of the slat outside of the niter zone, the

same rhomboidal form has the important advantage of shedding ordischarging the residual nitrate cleaning fluid away from the machine,so that injury to the metallic parts of the machine is prevented.Particularly is this important when the nitrate is of a characterdetrimental to .the materials of which the machine is constructed. Thetop walls of the slats |950 and lill' are each recessed as at |89 toprovide sufficient space between the closely super-imposed slats to Apermit the drainage of the nitrate from the niter .face to the rear ofthe siat, said space being necessary to prevent the blocking of thedrainage by nim production as otherwise results. 'I'he recessed portions|89 may be suitably sloped to deliver the nitrate thus drained topick-Yup means at any desired location between the two ends vof theslat. The inclined top and bottom walls of slats |90 and |90 causenitrate to be removed quickly from the proximity of the filter belts,cloths, or nlter faces and tend to prevent-'reabsorption of liquid byexpanding solid material at the location where pressure is released. Innd thatthere is a strong tendency for nitrate to be withdrawn from thesiat and re-absorbed by the solid material after said solid material haspassed the location of maximum pressure and has started to expand, saidexpansion exerting a vacuum like.- action. The slats shown in Figs. 25and 27 minimizes this tendency. by rapidly removing substantially all ofthe nitrate so that said nitrate has no opportunity to be thus drawnback and reabsorbed by the solid matter. Also in Fig. 25v I provide arelatively thin walled/pervious siat face |10' which cooperates topermit prompt drainage by retaining a thinner nlm of the nitrate in theinterstices o f the permeable siat` face. This thin slat face ispreferably reinforced by a plurality of webs |14 winch may parailel thetop and bottom walls of the slat. The

providing of a plurality of such web members also' provides for anincreased drainage surface to the tendencyof the nitrate tov nowbackwardly,

due to the vacuum produced by the expanding cake when the pressure isreleased. Drainage ports IBI' may be formed in the rear wail of slat|90' illustrated in Fig. 25 on the plane of each rib member |14'. vTherib members |14 are preferably provided with relativeiysharp and abruptfrontal edge portions ISI' to act as a dam to retard the return of thenitrate' to the said expanding cake due to the' suction `tendencyoccurring when the cake expands when the pressure is relieved. Ports|62' may be provided-in the rear wail above ports IGI' to admit air to.relieve any vacuum createdby the expanding 'cake without carrying thefiltrate back into the cake and without interfering with the drainage ofthe nitrate through ports Ill'. v

The siat l" shown in Fig. 27 diners in one respect yfrom the slat shownin Fig. 2 5 in that the front side of said slat is recessed'as at ISIfor the reception of a slatiface |52 which is formed of a plate or blockof porous niter material. Also inclined rib in Fig. 27 may havepassageway IN' adjacent the rear wall to permit nitrate topas's'downwardly to a discharge out- The two pendent frames lli, Figs. 1to 5 are connected with each other-by a plurality of noatingiy mountedtie rods' |83, which extend through the holes Ill in the outer ends ofthe u 'shaped cross'members |21. Relatively strongI soY and heavycompression springs |94 may be provided on the floatingly mounted tierods |93 at the outer sides of the U shaped cross members |21, and nuts|95 on the ends of said tie rods may serve as adjustable holding meansfor the springs |94. Suitable washers |99 may be provided at both endsof the springs |94. Due to the fact that the pressure between thependent frames increases toward the lower end of the machine, I preferto provide stronger oatingly mounted tie rod members and heavier springstoward the lower end. In Fig. 3, it will be noted that the lowermostsprings |94 are made larger and heavier. may be obtained toward thelower end oi' the pendent frames by providing a greater number ofsprings, which may be done as hereinafter more "fully described, withspecific reference to Fig. 45.

By interconnecting the two pendent frames' with the iloatingly mountedtie rods |93 it will be apparent that the pressure of material in thepressure chamber |39 between the two pendent frames will be borne as atension by said tie rods |93 and will not be transmitted to thestationary frame of the machine. This provides a balanced structure ofgreat strength and minimum weight and affords a very' advantageousconstruction for high pressure operation.

It will be noted .that rthe uppermost tierrods |93' which connect .fthetwo pendent frame members are positioned a short distance above thepivot screws ||1 on which said pendent frame members are swinginglysupported and that no springs are provided on these tie rods |93. Thisis more clearly shown in Figs. 1 to 4 inclusive. The nuts |91 on these-top tie rods are preferably non-rotatably secured to the cross members|21. This may be done by welding said nuts |91 to washers or plates |99which are welded to the cross members |21. The tie rods |93 each haveright hand threads at one end and' left hand threads at the other end,whereby rotation of said tie rods in one direction, withinl Itherelatively xed and non-rotatable nuts |91 will cause the two pendentframe members to be moved .toward each other and rotation of said .'tierods in an opposite direction will cause said .two pendent frame membersto be moved away from each other, it being apparent that each pendentframe member will be moved the same amount toward or away rfrom themedial vertical plane of 'the pressure chamber |39 in response torotation of the tie rods |93. To insure equal angular movemen-t of thetwo tie rods |93' in the same direction, I preferably provide a sprocketWheel |99 on each of said tie rods and I inter-connect said .twosprocket wheels by an endless link belt 2,00,

see Fig. 2. The tie rods |93' may be .turned by exerting a pull on thelink belt 200, it being understood that -these adjustments will' be madewhen the machine is inoperative and when the pendent frames are notsubjected to pressure.

' .and .that a small amount of power will sumce to ifrom being pressedtogether with the 4possibility 4 of damagingthe same when there is nomaterial in the chamber |38 of the machine. These sleeve members 20| areshownin Fig. 1.

The slat belts which are carried on the two Obviously more springpressurev pendent frame members |25 serve as supports for woven orfabricated iiltering members. Each tabricated filtering member may be inthe nature of an endless illter cloth belt 205 for use in connectionwith each slat belt, as shown by broken lines in Figs. 1 and 3, orit'may be in the nature of one or more straight strips of filter clothmaterial not in endless form', orit may be in the na- .ture of aplurality of superimposed illter cloth strips or belts all ashereinafter described and shown in the drawings. The endless lter belts205, shown in Figs. 1, 3, 4, 5 and 17 are wider than the slat belts and.the edges 205' of said filter belts fold over the ends of the slats |39as shown in Figs. 4, 5 and 17. These filter belts 205 pass aroundrollers 200, 201, 200 and 209 at Ithe upper end of the frame and aroundrollers 2|0 and 2| at the lower end of the frame, see Fig. 3. 'I'hey arepressed against the slat belts by the material within the pressurechamber |39, and movement may be imparted to -them -by the slat belts.In Fig. 3 the filter belts are shown as passingover the guide rollers206 just before they engage with the slat belts in their downwardmovement. In

Fig. 44 I have shown a guide member 2|2 posi tioned at the side of theslat belt near lthe upper end thereof and serving Ito fold the edge-ofthe filter `belt at right angles, whereby the edge of the illter beltmay be caused to fold correctly over the ends of thesla-ts |39 as itpasses in-to the pressure area of the machine.

Positioned at the sides of -the previously described slat belts and inengagement with the portions 205' of the filter cloths 205, which extendaround the ends of .the slats |39, are two side |belts 2|3, preferablyimpervious and preferably of metallic character to provide low friction.These side belts form walls of the pressure chamber |30 and may be ofduplicate construction. Each of the side belts 2|3 is carried on a slatbel-t composed of slats 2|! secured Ito .an endless link belt 2|5. 'I'helink belts 2|5 are mounted on upper sprocket wheels 2 6 and low-ersprocket wheels 2|1, see Fig. 2, and said link belts 2 I 5 have rollers2|9 provided on the pivot pins 2| 9, which connect the respective linksof said` link belts, see

Fig. 17. The rollers 2|9 may run on trackways 220, see Figs. 4, 9 and17, which may be positioned opposite the. sides of the pressure chamber|39 and extend between the upper and lower sprocket wheels 2|.9 and 2|1, respectively. The trackways 220 support the link belts 2|5 and slats2|! and said slats 2li support the impervious side belts 2|3 in closeliquid tight contact with the marginal portions 205' of the filter belts205, which marginal portions 205' are folded over the ends of 'the slats|39 .to provide a iiuid tight Joint between the ends of the slats `aridthe side belts. The trackways 220 for .the side belts may be supportedby flat springs 22| which extend cross wise of said trackways 220 atfrequent intervals, asshown in Figs. 4, 9 and 17. This track 220 isslightly flexible orresilient so that the same may be locally adjustedto make the joint between the side Vb elt vand the filter belts filtertight. The ends of the flat springs 22| have holes 222 for the receptionof portions 223 of reduced diameter on the ends of cap' screws 224,Figs. 4 .and 17. The cap screws 224 are .threaded through bosses 225 onthe upright side frame members l0, see-Fig. 4, and may be adjusted tovary the pressure of the side belts 2`I 3 against the ends of lthe slats|39 of the main slat bel-ts to make the joints of desired tightness.lThe ilat springs 22| are provided at frequent intervals and areadiustably

